<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .page {
        display: flex;
        height: 100vh;
    }
    .left{
        width: 200px;
        background-color: green;
    }
    .content{
        flex: 1;
        background-color: black;
    }
    .right{
        width: 200px;
        background-color: green;
    }
</style>
<body>
    <div class="page">
        <div class="left"></div>
        <div class="content"></div>
        <div class="right"></div>
    </div>
</body>
</html>